Protractor.



Patented 1an. I, I90I.

C. P. FAY.

PRUTRAGTUR.

4 (Applicgation led Jan. 30, 1899.\

(No Model.)

7? wmk A f /f,/W/+H Tn: noRms paens cn, uovo-nwo., WASHINGTON. n. c.

CHARLES P. FAY, OF CHICOPEE, MASSACHUSETTS, ASSIGNOR TO THE J. STEVENSARMS AND TOOL COMPANY, OF SAME PLACE.

PROTRACTO R.

SPECIFICATION forming part of Letters Patent N o. 665,316, dated January1, 1901.

Application tiled January SQ, 1899. Serial No. 708,799. (No model.)

To all w/tom, t 1er/ty concern.'

Be it known that I, CHARLES P. FAY, a citizen of the United States ofAmerica,and a resident of Chicopee, in the county of Hampden and Stateof Massachusetts, have invented certain nevt7 and useful Improvements inProtractors, of which the following is a full, clear, and exactdescription.

This invention relates to improvements in protractors of the classhaving combined with the graduated semicircular plate thecentrally-pivoted radins-bar or protractor-arrn, which is adapted to beswung at any angle from the base edge of the protractor-plate, whichdescription of protractor is extensively used by mechanics in settingbevel-squares or universal squares at any required angle, by draftsmenin setting T-squares with the blades thereof at any angle to the head,and by architects, surveyors, and others.

The invention more particularly relates to interlocking devices wherebythe radins-bar or protractor-arm after having been set at any anglerequired may be locked in its set position and held safely againstaccidental displacement, but susceptible of being readily disengaged andafterward lo'cked for a new setting of the bar, the object being toprovide a protractor of the kind referred to which is extremely simpleand cheap of construction, very convenient in operation, and accurate inits measuring or angle-indicating capability.

The invention in its broader aspect is defined as comprehending a newand improved protractor, consisting of a protractor-plate and aprotractor-arm or radius-bar pivoted thereon, the plate having a seriesof teeth or serrations corresponding to the degree-graduations thereonand the arm having a nnernber to register with theprotractor-graduations and provided with a device adapted for convenientdetachable engagements with the teeth of the plate; andthe inventionalso consists in the specic constructions and combinations of parts, allsubstantially as shown, described, and set forth in the claims.

Reference is to be had to the accompany-- ing drawings, in which thepresent improved adjustable protractor is fully and clearly illustrated,and in which- Figure l is a plan view thereof". Fig. 2 is a sectionalView on line 2 2, Fig. l. Fig. 3 is an edge view of the protractor,showing the protractorarm as swung into its position, whereby it isdisengaged from the protractorplate to permit the'adjustinent of saidarm at any angle from the base of said plate. Fig. t is a plan View ofportions of the protractorplate and of the protractor-arm, especiallyillustrative of the provisions whereby the one is detachablyintel-locked with the other. Fig. 5 is a sectional View similar to Fig.2,

but showing a slight modification.

Similarcharacters of reference indicate corresponding parts in all ofthe views.

In the drawings, A represents the protractor-plate, of substantiallyselnicircular form, having the straight base edge a, as usual, andhaving its face around adjacent its arc-formed edge provided with thedegree -indicating marks or graduations b, and the said arcformed edgeof the protractor is provided with a series of notches or teeth b,corresponding to and one for each of the graduations.

B represents the radius-bar or protractorarm lying under and next to theprotractorplate, being pivotally connected thereto by the headedscrewfand clam p-nut g, the extremity of said arm projecting beyond thetoothed edge of the protractor-plate, said extremity having formedthereon or permanently affixed thereto a member or shoe h, which isprovided at its inner edge with several teeth t, which are adapted toengage in the teeth edgewise provided on the protractorplate. The heightof the shoe, as shown, is approximately the same as the thickness of theplate, and the same is provided with the upstanding studj, having at itsupper end the overhanging head m. The height of the stud is slightlygreater than the thickness of the plate, and the head m is inwardlybeveled, as indicated at n, and is centrally provided with an indicatingmark or line o, extending centrally and longitudinally relative to theprotractor-arm.

In order to adj ust the protractor-arrn, which is of thin spring metal,the stud is pressed downwardly to bring t-he bevel-head to overlap andlie closely on the upper face of the protractor-plate, thereby causingthe shoe h IOO to be moved clear below the lower face of the protractor,the teeth of the shoe being disengaged from the teeth of theprotractor-plate, alias clearly indicated in Fig. 3. The protractor-armis now swung until the indicating-line o on the head of the stud comesto the graduation indicating the number of degrees at which theprotractor is to be set, whereupon the downward pressure is released,permitting the teeth of the shoe h to match into and interlock with theteeth of the plate, firmly assuring the retention of the bar in itsgiven set position, so that there will be no liability when theinstrument is placed against an adjustable square or other tool or workof the arm becoming displaced from its set position.

Vhile the description hereinabove given is specific in detailedstatement of the precise forms or construct-ions and arrangements of theparts of the protractor as shown in the drawings, I may, under theforegoing statement of invention and the terms of certain of my claims,carry out my invention by the employment of substantially the same ideaof means, but somewhat different in matters of detail-as, for instance,I may provide the protractor-arm B with the member or device forengaging the serrations or teeth of the protractor-plate, which memberis movable on or relative to the arm proper for the engagement anddisengagement with the teeth of the plate, and in Fig. 5 the radius-baror protractor-arm B is constructed in the two sections o and 02, the oneof which is engaged with the other for an endwise sliding movement, aspermitted by the pin-and-slot engagemen t, (indicated at t.) Thereforeunder this construct-ion a distention of the radiusbar, instead of abending thereof across its normal plane of occupancy, enables thedisengagement of the teeth i' of the part hat the outer extremity of thebar from the teeth or seri-ations at the edge of the protractor-plate.

Having thus described my invention, what I claim, and desire to secureby Letters Patent, is-

l. A protractor-plate having a series of degree-graduations, andprovided with a series of corresponding teeth, combined with aprotractorarm pivotally connected to swing around on the plate, carryingan indicating part to register with the said graduations', and having apart movable relatively to the teeth of the plate, to engage anddisengage the same.

2. A protractor-plate having graduations, and edgewise provided withcorresponding teeth, combined with the pivotally-connectedprotractor-arm constructed with a portion or member projected beyond theedge of the plate, and provided with an upstanding part which at itsedge toward the plate is toothed, the said arm which carries theupstanding part being composed of spring metal and capable of beingswung transversely of the plane of the plate for disengagement andrengagement with the latter, substantially as described.

3. A protractor-plate having graduations and edgewise provided withteeth corresponding thereto combined with a protractor-arm of springmetal pivotally connected to the plate and having at its extremity whichis projected beyond the edge of the plate, the upstanding shoe h whichat its edge toward the plate is toothed, and said extremitiesfurthermore having the upstanding stud with the head which overhangs theedge of the protractor-plate, and which has an indicator to registerwith the graduations of the plate, substantially as described.

1. The combination with 'the protractorplate having thedegree-graduations and corresponding edgewise serrations or teeth, ofthe protractor-arm B pivotally connected to the base portion of theplate and having its free extremity extended beyond the curved edge ot'the plate and provided with the shoe 7L having at its edge toward theplate the teeth 'i and having the upstanding stud j of a height slightlygreater than the thickness of the plate and provided with the head mwhich overhangs the edge of the plate, and which has the beveled part nprovided with the indicatingmark o,all substan tially as described andshown.

Signed by meat Springfield, Massachusetts, this 4th day of November,1898.

CHARLES P. FAY.

Witnesses:

WM. S. BELLOWS, M. A. CAMPBELL.

